There is a water discharge apparatus that automatically controls the water discharge and shutoff by using a photoelectric sensor to detect an object such as a hand of a user, etc., and by operating an opening/closing valve. For example, such a water discharge apparatus is applied in a faucet apparatus, a urinal, a commode, etc.
The photoelectric sensor includes a light-projecting element projecting detection light such as infrared light, etc., includes a light receiving element receiving reflected light of the detection light reflected by the object, and outputs a received signal corresponding to a light reception amount of the light receiving element. For example, the water discharge apparatus starts the water discharge when the received signal exceeds a prescribed threshold, and stops the water discharge when the received signal is less than the threshold.
In the photoelectric sensor, the effects of electromagnetic noise entering from the outside are suppressed by covering, with a shield member, the periphery of the sensor main body of the light-projecting element, the light receiving element, etc. (e.g., Patent Document 1). The shield member includes, for example, a conductive material such as copper, aluminum, etc. The shield member is electrically connected to a reference potential (e.g., ground) of the sensor main body. Thereby, the incidence of the electromagnetic noise on the sensor main body is suppressed.
In the photoelectric sensor, a light-shielding conductive material such as a metal, etc., cannot be used to cover the front of the light receiving element because the reflected light is undesirably blocked. Therefore, there are cases where the received signal that is output is undesirably unstable due to the electromagnetic noise entering from the front. Unintended fluctuation of the received signal causes erroneous water discharge of the water discharge apparatus; and there is a possibility that the water discharge may be performed even though the object does not exist, or conversely, the water discharge may not be performed even though the object exists.
If the configuration for suppressing the electromagnetic noise entering from the front of the light receiving element becomes complex, this undesirably causes an increase of the manufacturing cost of the photoelectric sensor. Therefore, in the photoelectric sensor and the water discharge apparatus using the photoelectric sensor, it is desirable to suppress the electromagnetic noise entering from the front of the light receiving element by using a simple configuration.